An apparatus for making a plurality of textile fiber strands is known which has a multiplicity of receiving members for receiving the fiber strands made in a plurality of principal or main time intervals.
These receiving members (e.g. spools) are replaced by empty receiving members in intermediate time intervals between principal time intervals. A plurality of manufacturing devices work together to make the fiber strands which are fed to the receiving members and are driven by a principal drive unit.
These manufacturing devices have at least one alternating current motor and at least one frequency converter. One of the frequency converters acts to supply at least one of the alternating current motors of the principal drive unit with an adjustable frequency current.
The apparatus also has at least one auxiliary drive unit which at least acts to supply power for changing the receiving members in an intermediate or intervening time interval.
By alternating current motors I mean standard electric motors which are supplied with a single or polyphase current. Synchronous or asynchronous motors can be used. Advantageously the alternating current motors can be polyphase motors.
My invention can advantageously be applied to spinning machines, drafting rolls and flyers.
The spinning machine can advantageously be a ring spinning machine, a bell spinning machine, combing machine or the like. The apparatus however can comprise a part or portion of a machine or of several machines connected together.
A ring spinning machine can often be divided into two or more portions producing yarn independently of each other, for example, into two longitudinal machine halves. Here each longitudinal machine half is a device for making fiber strands.
It can comprise several carding devices connected with a set of drafting rolls or a drafting mill associated with them producing a fiber strand.
The replaceable receiving members of such fiber manufacturing unit include spinning cans, spools or bobbins. However there are also other receiving members, for example spinning tops in spinning top spinning machines.
These machines manufacture or process roving, fiber strands, yarn or thread, hereinafter referred to generically as fiber strands.
In the textile fiber strand making unit described above there is a main drive unit which acts to drive its producing components. By producing components I mean here all parts which work together in making the fiber strands winding them on spools, bobbins or the like or feeding them into cans, spinning tops or the like.
During an intervening time interval the receiving members no longer are fed with fiber strands. However it is possible in many cases to make fiber strands for a short time at the beginning of an intervening interval.
Then the fiber strands are not conducted to the receiving members but to other locations in the unit, e.g. to lower winding positions of the spindles of the ring spinning machine where they are wound.
A main time interval thus begins after an exchange of the receiving members as soon as the initially empty receiving member starts to be supplied with some fiber strand and ends when the loading of the receiving member with fiber strands ends for the purpose of the replacement.
During the intervening time interval the full receiving member now fully loaded during the previous main time interval is replaced by an empty receiving member.
The production of the fiber strands and their feeding to the receiving member can then begin again, i.e. then a main time interval starts.
During a main time interval the fiber manufacturing unit produces fiber strands uninterruptedly. It is also possible to interrupt this production without changing the receiving members. Such interruption times are counted as part of the main time interval.
In the unit to which the invention is related the main drive unit can have a single electric drive motor in many cases which is normally an asynchronous motor supplied with three phase current which is supplied by a frequency converter and is controllable in its rotation speed by adjustment of the output frequency of the frequency converter. This control allows adjustment of the rotation speed of this motor continuously or in steps by a frequency converter corresponding to a continuous or stepped adjustment of the output frequency thereof.
However in some manufacturing units, the main drive unit has many electrical alternating current motors instead of a single drive motor. It can be associated with or provided with a common frequency converter or a number of frequency converters to supply only one motor or a portion of the motors of the main drive unit and to supply the other motors of the main drive unit in another way, for example advantageously directly from the a.c. line current source. It is known to drive each spindle of a ring spinning machine individually by its own alternating current motor and to drive the drafting rolls by another or several other alternating current motors.
One common frequency converter can then be associated with all these motors or only the spindle drive motors or only the drive motors for the drafting rolls.
It is also possible to provide several frequency converters for all these motors.
In such a unit it is frequently the case that an automatically operating changing device is provided for replacement of full bobbins or receiving members with empty bobbins or receiving members. This changing device is drivable using an auxiliary drive unit.
Also one or more auxiliary drive units can be used for other purposes, e.g. for ring banks of a ring spinning machine or the ring bank of one half of a ring spinning machine after disconnecting the ring spinning machine during its run down period so that the yarn produced during the run down period is not wound on the bobbins but on the lower winding locations of the spindle.
At least one auxiliary drive unit can be provided for the drive of some other aggregate or member, e.g. cleaning devices performing cleaning tasks in the intervening time interval and/or control devices performing control operations and/or restoring devices performing restoring operations.
Frequency converters are comparatively expensive. For this reason in many applications, economical pole changing alternating current electric motors may be provided even though the frequency converter in itself is better for the rotational speed control of the alternating current motor on account of the stepwise continuous frequency variation of the current of the alternating current motor. Pole changeable electric motors allow only a few different rotation speed steps while the output frequencies of the frequency converters are adjustable over a wide range continuously or if necessary in small steps. Thus the rotation speed of each of the alternating current motors is more readily controllable with frequency converters. Also pole changeable motors are comparatively large and require more space than alternating current motors which are not pole changeable.